Tennis

Tennis players would agree that the impact of new materials on the game has resulted in a revolutionary change in the way the game is played: the dominance of the serve has resulted from the improvements in racket construction. Among these improvements are a reduction in mass and an increase in stiffness.  

Rackets have evolved quite dramatically over the last 50 to 100 years. The first rackets were made from solid sections of wood, often ash or maple. Wood is a natural composite material consisting of elongated cells contained within a resin and it is anisotropic, i.e. it is much stiffer along the grain of the wood. 

Hence tennis rackets that were constructed from solid sections of wood suffered from the disadvantage of low stiffness perpendicular to the grain. 

A revolutionary change in racket technology occurred when carbon fibre reinforced plastic (CFRP) composites were introduced. These materials gave rackets that are much stiffer, lighter and long lasting. 

A modern racket incorporates different materials to achieve the ideal. The mass is kept low by the use of fibre-reinforced material, with a combination of fibres. Carbon fibres are used to increase the stiffness and comprise 80 % of the total amount of fibres. The remainder are aramid fibres, which introduce a level of damping into the frame. The matrix is often based on epoxy resin, which is a high stiffness matrix. To provide additional vibration damping, an expanded polyurethane foam is used as the core of the racket.